1. Field of the Invention
This invention relates to adsorbents for heavy metal ions. More particularly, it is concerned with novel adsorbents for heavy metal ions, which are cyclic tetramines containing specific substituents and synthetic resins with the cyclic tetramines bonded thereto.
2. Description of the Prior Art
Heavy metal ion adsorbents hitherto used to remove heavy metal ions contained in waste water, such as copper, nickel, mercury and the like ions include activated carbon, kieselguhr, ion exchange resins, chelate resins and the like. These adsorbents, however, have disadvantages; activated carbon, kieselguhr and ion exchange resins are inferior in selective adsorption ability for heavy metal ions, and chelate resins are inferior in selectivity, particularly among heavy metal ions.
Thus, heavy metal ion adsorbents have long been desired which do not have the disadvantages of the conventional adsorbents.